As the series progressed, Montag began dating fellow cast member Spencer Pratt, which ultimately ended her friendship with Conrad.

In January 2010, Montag released her debut studio album Superficial; it was critically panned and commercially unsuccessful at the time, failing to earn back the money she spent making it, but would go on to garner a cult following.

During freshman orientation, she befriended Lauren Conrad, who at the time was a primary cast member of the MTV reality television series Laguna Beach: The Real Orange County.

After both transferred to the Fashion Institute of Design & Merchandising in Los Angeles, California, Montag was subsequently featured in four episodes during the series' second season.

[9][10] [11] After moving to Los Angeles in 2006, the Laguna Beach spin-off series The Hills was developed to chronicle the lives of then-housemates Conrad and Montag and friends Audrina Patridge and Whitney Port.

[28] After leaving the series, Montag and Pratt became notorious for their antics and antagonistic roles, notably during an interview with Al Roker of Today,[29] and were described as "everything that's wrong with America".

[34] In January 2010, Montag revealed to People that she had undergone ten cosmetic surgery procedures in a single day two months prior, performed by Frank Ryan.

[36] The self-funded record cost nearly $2 million and sold approximately 1,000 copies in first-week downloads, failing to earn back the money spent making it.

[44] Later that year, she appeared on the VH1 reality television series Famous Food, where she competed against other celebrities for a partnership stake in a restaurant in which they worked to open.

[47][48] In January 2013, Montag and Pratt as a single entity competed as housemates on the eleventh series of the British version of Celebrity Big Brother,[49] where they notably developed a minor feud with singer and television personality Rylan Clark.

[51] On February 18, Channel 5 aired a one-off television special discussing Montag and Pratt's rise to prominence, titled Speidi: Scandal, Secrets & Surgery!.

[52] Later that year, they launched the Speidi Show, which was initially assumed to be a web series in which the couple used a different reality television format for each installment.

However, the project was later revealed to be an example of networked improv narrative, where Montag and Pratt collaborated with Mark Marino and Rob Wittig to create a Twitter game in which players Live Tweet an imaginary show.

[54] In December 2013, Montag stated that she and Conrad have "talked a few times" since the series' conclusion, elaborating that "it's unfortunate things happened the way that it did, but we're both different people now, older and more mature.

She and Pratt appeared in the television special After Shock: Heidi & Spencer, which premiered on December 9, 2013, on E!, during which they admitted that many of the situations they were involved with in the various reality series they starred on were in fact made up by the shows producers.

Due to the song gaining traction, Montag expressed her desire to return to the music industry and released her comeback single "Wet Hot Summer" on June 28, 2024.

Montag's version then leaked and received negative reviews from critics, which then led to Gaga releasing the song, which was featured on the soundtrack for the 2009 film Confessions of A Shopaholic.

[65] In January 2025, a decade after its original release, Montag's album Superficial, topped the iTunes music charts in the United States, Australia, New Zealand, Canada, Sweden, Norway, the Netherlands, and Oman.